The present invention relates generally to intravascular devices that incorporate an inflatable member, and more particularly to devices of this type which enable rapid and efficient degassing of the device. The present invention also relates to methods for rapidly and efficiently degassing an intravascular device that incorporates an inflatable member.
During the course of many medical procedures, it is often necessary to introduce a catheter or cannula that incorporates an inflatable member, such as a balloon catheter, into the circulatory system of the patient. However, before such a device can be safely utilized, the physician, or other qualified medical personnel, must institute a degassing process. That is, gasses, such as air, entrained in the device during manufacturing and packaging must be displaced so that if the inflatable member should leak or rupture during use, the chance of gas being released into the circulatory system is minimized.
For example, when utilizing PTCA catheters or intra-aortic balloon occlusion catheters/cannula, medical personnel must typically perform repeated liquid inflation and deflation cycles prior to placement of the device, in an effort to remove all entrapped air from the inflatable member. This tedious process is often difficult to accomplish. Furthermore, the degassing process is time consuming, inconvenient, and costly.
The need to perform numerous inflation and deflation cycles in an effort to remove all entrained gasses can also severely limit the design of the overall device. In particular, intravascular devices that have a large volume of inflation tubing in comparison to the overall volume of the inflatable member tend to be especially difficult to degas.
Accordingly, there is a need for an intravascular device that incorporates an inflatable member, such as a balloon catheter, which permits rapid and efficient degassing of the device. Furthermore, there is a need for such a device which also places few, if any, restrictions on design choices. The present invention satisfies both of these needs.
The present invention relates to medical devices and their methods of use, particularly intravascular catheters and cannula which incorporate an inflatable member. The intravascular device of the present invention generally includes three components, namely: (1) a catheter or cannula; (2) an inflatable member; and (3) a selective degassing element.
The inflatable member is typically a balloon having a defined interior. The balloon is capable of expansion to a defined volume when the interior of the balloon is infused with liquid.
The catheter or cannula is typically hollow. The proximal end of the catheter or cannula incorporates an inflation port. The distal end of the catheter or cannula incorporates an exhaust port. A first lumen extends within the catheter or cannula from the inflation port to the interior of the inflatable member. A second lumen extends within the catheter or cannula from the exhaust port to the interior of the inflatable member. The first lumen enables liquid, infused into the catheter or cannula through the inflation port, to flow into the interior of the inflatable member. The second lumen enables gas, entrained within the interior of the inflatable member, to be expelled from the catheter or cannula through the exhaust port.
The selective degassing element typically occupies the entire cross-sectional area of the second lumen and is preferably positioned across the second lumen near the exhaust port. When in a closed position, the selective element prevents the passage of liquid from the interior of the inflatable member, through the exhaust port, via the second lumen. However, when the selective element is in an open position, the gas entrained within the inflatable member is permitted to pass through the second lumen to the exhaust port. This flow of gas may be expedited, in some instances, by the infusion of liquid into the device through the inflation portxe2x80x94causing any gas entrained within the first lumen, the second lumen, or the interior of the inflatable member to migrate toward the selective degassing element, pass through the selective degassing element, and be expelled from the catheter or cannula through the exhaust port.
The selective degassing element can take a number of forms and can be placed in an open or closed position in a number of ways. In certain embodiments, the selective degassing element is a non-mechanically actuated valve, a plug, a membrane, a mechanically actuated valve, or a hydrophobic filter. The non-mechanically actuated valve, the plug, and the membrane are typically in a closed position unless placed in an open position by insertion of a needle or hollow tube. The hydrophobic filter is always in an open position.